In recent years, researches have been advanced on organic light-emitting devices including light-emitting layers that include an organic light-emitting material. An organic light-emitting device for example includes a thin-film transistor (TFT) substrate, anodes, light-emitting layers, and a cathode. Also, an organic EL element includes hole injection layers, hole transport layers, an electron injection layer, an electron transport layer, a sealing layer, and so on as necessary. Examples of the organic light-emitting device include an organic EL display panel having a plurality of pixels.
By the way, an organic EL display panel of an active matrix driving type generally includes an anode as an electrode that is formed independently for each pixel and a cathode as an electrode that is formed for the entire pixels. Voltage is applied to the cathode from a peripheral part of the cathode. Accordingly, the size increase of the organic EL display panel causes voltage drop due to the increase of an electrical resistance of the cathode itself. Variation might occur in voltage to be applied between the anode for each pixel and the cathode because of the difference in distance from the peripheral part of the cathode to each pixel. Such a variation in voltage to be applied between the anode for each pixel and the cathode results in luminance unevenness in the organic EL display panel. To address this problem, Patent Literature 1 discloses a technology of preventing variation in voltage to be applied between an anode for each pixel and a cathode by electrically connecting wirings and the cathode that are disposed on a substrate. Such electric connection is often established by direct contact of the wirings with the cathode.
On the other hand, a wet process is sometimes used in a panel manufacturing process. There is for example a case where an interlayer insulating layer to be formed on a TFT circuit, a barrier rib layer constituting subpixels of RGB luminous colors, and so on are formed by application of a positive photosensitive material. There is also a case where a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and light-emitting layers, which constitute an organic EL element, are formed by application of an ink containing an organic material. Layers formed by the wet process might contain moisture and oxygen. Also, formation by the wet process sometimes results in a cathode made of a metal, an organic functional layer including a metal, and so on. In this case, if moisture and oxygen intrude into the cathode and the organic functional layer from the light-emitting layers, the cathode and the organic functional layer might degrade due to oxygenation of the metal included therein, for example. To address this problem, Patent Literature 2 discloses a technology of providing, between light-emitting layers and an organic functional layer, an intermediate layer including fluoride of an alkali metal or an alkaline-earth metal.